SCARY water leak out the side wall of my in-ground pool

[Dirk]

So I waited for several days and the wall leak has almost stopped, water level is still ok. So at least part of initial problem could have been just overfilling the pool. PebbleTec crack is above water line and will still be dealt with in due course.

There is a very slight wall leak still, no longer starting at beam level but a few feet lower, and I noticed that the pool light is at about that level and appears partly unseated (pic below). Does that look like a candidate for the small remaining leak? The leak is likely too small for leak-detector to show ink trail.
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If I understand lights (which may or may not apply to yours), it is not the light or its frame that provides the seal. It is the plaster/pebble sealing to the light niche that does that. The niche should be water tight whether there is a light installed or not, or even if the light is installed cattywampus.

The niche will have a conduit exiting it, where the cable goes through. That conduit is typically full of water, its entire length, until it turns upward and comes out of the ground. So even if the niche is sealed well to the plaster, the leak could be in the junction of the conduit to the niche, or anywhere along the conduit (underground).

You can try removing the light from the niche and let it just hang down, still in the pool, or set it on the deck (there should be cable enough stuffed into the niche to do that). That shouldn't make a difference in the leak, but it might allow you to do a better job with the ink test.